The Chesapeake Bay is our nation's largest estuary. An American treasure of legendary beauty, the bay and its system of tributary rivers and streams are critically important — economically, culturally, and for human health reasons. Yet, they remain fouled by pollution that runs off farm fields and city streets, falls from the air, and is deposited directly from point sources such as sewage-treatment plants and factories.

The state of the bay system is a national embarrassment.

The bay's geography at the center of the mid-Atlantic region and in the backyard of the District of Columbia ensures that the entire country is watching efforts to restore good water quality. For that reason, recent reports that pollution-reduction efforts languish, especially in my home state of Pennsylvania, are concerning.

We as a society have long acknowledged the problem and long committed to resolving it. In fact, as governor of Pennsylvania between 1979 and 1987, I was one of five signatories to a regional commitment to restore the bay.

That commitment, called the 1983 Chesapeake Bay Agreement, was also signed by the governors of Maryland and Virginia, the mayor of the District of Columbia, and the administrator of the Environmental Protection Agency (EPA).

Our agreement began:

"We recognize that the findings of the Chesapeake Bay Program have shown an historical decline in the living resources of the Chesapeake Bay and that a cooperative approach is needed among the Environmental Protection Agency, the state of Maryland, the commonwealths of Pennsylvania and Virginia, and the District of Columbia ... to fully address the extent, complexity, and sources of pollutants entering the Bay.

"We further recognize that EPA and the states share the responsibility for management decisions and resources regarding the high-priority issues of the Chesapeake Bay."

The 1983 agreement established an executive council, whose role was, and still is, to:

"Assess and oversee the implementation of coordinated plans to improve and protect the water quality and living resources of the Chesapeake Bay estuarine systems."

Roughly half of Pennsylvania drains into the bay. We deliver half of the fresh water entering the Chesapeake and, overall, the most pollution degrading it.

I am deeply troubled that our state contributes so much pollution and has made relatively little progress to slow that pollution, adversely affecting water quality in Pennsylvania and, ultimately, the bay.

The annual meeting of the executive council is scheduled for Thursday. When the council gathers, it must commit to action, and now. The commitments must be clear, specific, and measurable.

The nearly 18 million people living in the bay states should not have to wait another 30-plus years for the clean water promised to all of us in our nation's Clean Water Act.

Dick Thornburgh is a former governor of Pennsylvania.  dick.thornburgh@klgates.com